Some imperfections in the randomization procedures affecting a small subset of participants in the PREDIMED trial (at most 14%) have been recently reported (1). For this reason, we wish to make the following statements concerning our original paper on Mediterranean diet and risk for type 2 diabetes (2).

First, the randomization was concealed with the use of closed envelopes only during part of the pilot phase of the study, but envelopes were not used for the remainder of the study.

Second, a corrected flow diagram (Figure 1 in the original study) is shown here. It now contains information on the small number of participants allocated in clusters (households or clinics) instead of being individually randomized.

Finally, we have reanalyzed the effect of the intervention on the incidence of type 2 diabetes (2) adjusting for propensity scores (built with 30 predictors of allocation) and using a robust estimate of the variance to correct for intra-cluster correlation (Correction Table). This table includes a sensitivity analysis after excluding the second household members not randomized and the participants allocated in clusters (clinics) instead of individual allocation from one of the 11 recruitment sites (Site D).

Of note, the key message from the original article does not change and the final conclusions remain the same.

Corrected Figure 1.

Study flow diagram.

EVOO = extra virgin olive oil; MedDiet = Mediterranean diet.

Correction Table. Risk for Incident Type 2 Diabetes According to the Intervention Group in the PREDIMED Trial, 2003-2010

Correction Table. Risk for Incident Type 2 Diabetes According to the Intervention Group in the PREDIMED Trial, 2003-2010

Corrected Figure 1.

Correction Table. Risk for Incident Type 2 Diabetes According to the Intervention Group in the PREDIMED Trial, 2003-2010

Correction Table. Risk for Incident Type 2 Diabetes According to the Intervention Group in the PREDIMED Trial, 2003-2010

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